Real Dictionary

roll on in British English
adjective: (of a deodorant, lip gloss, etc) dispensed by means of a revolving ball fitted into the neck of the container
noun: a woman's foundation garment, made of elasticized material and having no fastenings
verb: used to express the wish that an eagerly anticipated event or date will come quickly

roll-on
A roll-on is a deodorant or cosmetic that you apply to your body using a container with a ball which turns round in the neck of the container.

roll-on in American English
designating any of various commercial products, as a deodorant lotion, that are applied to the skin by means of a rotating ball within the top of the dispenser
such a product
adjective: packaged in a tubelike container one end of which is equipped with a rotating ball that dispenses and spreads the liquid content directly
noun: a roll-on preparation

roll-on in British English
adjective: (of a liquid cosmetic, esp a deodorant) packed in a container having an applicator consisting of a revolving ball
noun: a liquid cosmetic, esp a deodorant, packed in a container having an applicator consisting of a revolving ball